> You need to spend $834 locally to get 1,000 Premiermiles.
> To get 54,500 miles, you need to spend $45,416.67 locally.

If you spend $1,000 per month, you need 39 months to chalk 54,500 miles.
If you spend $2,000 per month, you need 19.5 months to chalk 54,500 miles.

Of course, there are other methods to gain points, like making overseas purchases with the same card gives you a rate of 1.5 miles. Or using alternative cards to make expensive purchases for better points/cashback.